The invention relates to burner devices. More particularly, the invention relates to a burner module for producing an inorganic soot.
The formation of inorganic soot, particularly metallic oxide soot, produced by reacting a precursor in the flame of a burner is well known. Soot generated by such a reaction has been used to form articles such as, for example, crucibles, tubing, lenses, and optical waveguides by depositing the soot on a receptor surface.
The formation process for such articles from inorganic soot generally involves delivering a silicon-containing precursor to a burner and reacting the precursor in a burner flame generated by a combustible gas, such as a mixture of methane and oxygen. Historically, halide-containing precursors, such as silicon tetrachloride and mixtures of silicon tetrachloride with various dopants, have been used for producing preforms by vapor phase deposition techniques such as, for example, VAD (vapor axial deposition) and OVD (outside vapor deposition).
In these procedures, typically a vapor delivery process is utilized in which halide-containing raw materials are vaporized at a location remote from the burner. The vaporized raw materials are then transported to the burner by a carrier gas where they are volatilized and hydrolyzed to produce soot particles which are collected on a receptor surface.
Among the burner modules that are currently being used to generate soot in these applications are multilayer modules fabricated from silicon and Pyrex® glass. The performance of such burner modules is limited by their poor resistance to thermal shock. Burner modules made using conventional machining suffer from the lack of repeatability and size limitations, which manifest themselves in non-uniform flame fronts or restrictions of maximum flow.